The driving of an aircraft on the ground, and in particular the control of the aircraft around its yaw axis, is generally provided by controlling the steering angle of the nose gear wheel, by the orientation of the rudder, and in addition by a differential braking assembly able to exert a braking differential between a left main landing gear and the right main landing gear to generate the yaw movement. The control of the aircraft around its yaw axis may further be done using electric motors driving the wheels of the main landing gear, at different speeds and/or by applying a thrust differential between the left engine and the right engine.
Various control means are known to command these different lateral movement devices.
In particular, some aircraft include three separate control means each acting on one of the aforementioned lateral movement devices. These control means for example consist of a tiller, a rudder bar and independent brake pedals.
The tiller is a control wheel whose rotation makes it possible to cause a corresponding modification of the steering angle of the wheel.
The rudder bar is intended to control the rudder. In particular, the rudder bar generally includes a left pedal, the movement of which is intended to control a left turn, and a right pedal, the movement of which is intended to control a right turn.
The brake pedals include a left brake pedal and a right brake pedal, the actuation of which is intended to command braking of the left or right main landing gear, respectively, therefore a turn to the left or to the right, respectively.
The brake pedals are for example mounted on the rudder bar. Thus, each rudder bar pedal is movable along a first degree of freedom, for example in translation, associated with a command of the rudder, and along a second degree of freedom, for example in rotation around an axis orthogonal to the translation direction of the pedal, associated with a command of the differential braking assembly.
Alternatively, it has been proposed to include the control of the steering angle of the nose gear wheel in the rudder bar.
These solutions may be subject to improvement.
In particular, the simultaneous management of the control orders to be issued via the rudder bar and those to be issued by actuating the tiller or the brake pedals induces a substantial workload for the pilot.
Furthermore, such a control system leaves the pilot complete latitude for the use of the various lateral movement devices.
Yet under certain circumstances, using the differential braking assembly may have drawbacks, and may in particular prove uncomfortable for the passengers of the aircraft or cause heating of the braking devices leading to damage.
Furthermore, when the brake pedals are mounted on the rudder bar, the movements of the pedals along both degrees of freedom are not coupled, such that actuating only the differential braking assembly to apply a given braking force differential, only the rudder to steer said rudder at a given angle, and simultaneously actuating the differential braking assembly and the rudder may prove difficult and imprecise, and therefore generate a substantial workload for the pilot.
One aim of the invention therefore consists of providing a system for controlling a lateral trajectory of an aircraft generating a minimal workload for the pilot, while minimizing the risks related to using the differential braking assembly.
To that end, the invention relates to a control system of the aforementioned type, characterized in that each of the left and right pedals can be moved between the neutral position and an end-of-travel position along a single preset travel, a movement of the left pedal, respectively of the right pedal, along said preset travel, between the neutral position and a predetermined differential braking activation position, being intended to command a movement of the aircraft around the yaw axis along a first direction, respectively a second direction opposite the first direction, by actuation of at least one movement device of the first assembly, the differential braking assembly being nonactive, a movement of the left pedal, respectively of the right pedal, along said preset travel, from the differential braking activation position toward the end-of-travel position being intended to command a movement of the aircraft around the yaw axis along the first direction, respectively the second direction, by actuation of at least one movement device of the first assembly, and by actuation of the differential braking assembly, the differential braking assembly being active, and in that the rudder bar includes a haptic feedback generator configured to apply, to each of the left and right pedals, a first haptic profile when the left, respectively right, pedal is moved from the neutral position to the activation position, and a second haptic profile, distinct from the first haptic profile, when the left, respectively right pedal is moved from the activation position to the end-of-travel position.
The control system according to the invention may comprise one or more of the following features, considered alone or according to any technically possible combination:                the haptic feedback generator is configured to apply, to each of the left and right pedals, a force opposing the actuation of the pedal according to a first force profile when the left, respectively right, pedal is moved from the neutral position to the activation position, and according to a second force profile, distinct from the first force profile, when the left, respectively right pedal is moved from the activation position to the end-of-travel position.        the haptic feedback generator is configured to apply, to each of the left and right pedals, a force opposing the actuation of the pedal, such that the first derivative of the force opposing the actuation of the pedal from the activation position to the end-of-travel position is strictly greater than the first derivative of the force opposing the actuation of the pedal to the activation position.        the first derivative of the force opposing the actuation of the pedal from the differential braking activation position to the end-of-travel position is strictly greater than any first derivative of the force opposing the actuation of the pedal from the neutral position to the differential braking activation position.        said preset travel is a movement of said pedal chosen from among: a translational movement, in particular a straight or circular translational movement, and a rotational movement.        each of the left and right pedals is further movable between a rear position and the neutral position, the neutral position being between the rear position and the end-of-travel position, and in that the system includes a mechanism for coupling the movement of the left and right pedals, configured, when the left pedal, respectively the right pedal, is moved toward the end-of-travel position, to drive a movement of the right pedal, respectively of the left pedal, toward the rear position.        said preset travel is a movement of said pedal according to a single degree of freedom.        the differential braking activation position is a preset fixed position of the pedal along said preset travel.        the control system includes a regulating module, configured to determine a threshold value of a trajectory parameter at least at one moment during the movement of the aircraft on the ground, as a function of at least one criterion chosen from among a piece of information relative to the current speed of the aircraft, a current runway state, an operating state of the nose gear wheel and a temperature of braking devices of the differential braking assembly, the threshold value being representative of a first limit trajectory able to be reached by the aircraft by actuating at least one lateral movement device of the first assembly, the differential braking assembly being nonactive.        the haptic feedback generator is configured to determine the activation position as a function of said threshold value, and to determine the first and second haptic profiles as a function of said activation position.        the control system comprises a device for acquiring a current position of said left pedal and a current position of said right pedal, said positions being representative of an instruction lateral trajectory.        the control system includes a trajectory control module configured to, selectively:                    if none of the current positions of the left and right pedals are between the activation position and the end-of-travel position, send at least one input instruction to at least one lateral movement device of the first set, to the exclusion of the differential braking assembly, said input instruction being configured to create, when it is applied to the lateral movement devices of the first set, the differential braking assembly being nonactive, a lateral movement of the aircraft according to or tending toward the instruction lateral trajectory,            if the current position of the left pedal or right pedal is between the activation position and the end-of-travel position, send input instructions to at least one lateral movement device of the first set and the differential braking assembly, said input instructions being configured to create, when they are applied to the lateral movement device of the first set and the differential braking assembly, a lateral movement of the aircraft according to or tending toward the instruction lateral trajectory.                        the differential braking assembly includes a braking device of a left main landing gear and a braking device of a right main landing gear, the differential braking assembly being configured in order, in the active state, to the exclusion of the nonactive state, to exert, at a given moment, a left braking force on the left main landing gear and a right braking force, distinct from the right braking force, on the right main landing gear, in order to generate a movement of the aircraft around the yaw axis.        the lateral movement devices further include a set of electric motors configured in order, in an active state, to the exclusion of a nonactive state, to apply a speed differential between the left main landing gear and a right main landing gear to generate a movement of the aircraft around the yaw axis, the movement of the left pedal, respectively of the right pedal, between the neutral position and the differential braking activation position is intended to command the movement of the aircraft around the yaw axis by actuating at least one movement device of the first assembly, the differential braking assembly and the set of electric motors being nonactive, and the movement of the left pedal, respectively of the right pedal, from the differential braking activation position toward the end-of-travel position is intended to command the movement of the aircraft around the yaw axis by actuation of at least one movement device of the first assembly, and by actuation of the differential braking assembly and the set of electric motors, the differential braking assembly and the set of electric motors being active.        the control system includes a module for determining ground trajectories of the aircraft, configured to determine, at least at one moment:                    a current trajectory of the aircraft on the ground, including a series of waypoints predicted for at least one element of the aircraft, under unchanged conditions of the lateral movement devices of the set and the differential braking assembly,            at least a first limit trajectory, including a series of first limit waypoints that may be reached by the element of the aircraft by actuating the left pedal and/or the right pedal between the neutral position and the differential braking activation position,            at least a second limit trajectory, including a series of second limit waypoints that may be reached by the element of the aircraft by actuating the left pedal or the right pedal between the differential braking activation position and the end-of-travel position, and the control system includes a display assembly comprising:            a viewer, configured to display a view of a runway portion located near the aircraft;            a display generating module, configured to display, on the viewer, a current trajectory curve representative of said current trajectory, at least a first limit curve representative of the first limit trajectory, and at least a second limit curve representative of the second limit trajectory, said curves being superimposed on the view of the portion of the runway.                        